# git rev-parse -q --verify 6a86fe746e2f69e49328b9ad8ad0f840c467ee59^{commit}
6a86fe746e2f69e49328b9ad8ad0f840c467ee59
already have revision, skipping fetch
# git checkout -q -f -B kisskb 6a86fe746e2f69e49328b9ad8ad0f840c467ee59
# git clean -qxdf
# < git log -1
# commit 6a86fe746e2f69e49328b9ad8ad0f840c467ee59
# Author: Michael Ellerman <mpe@ellerman.id.au>
# Date:   Thu Feb 18 23:30:58 2021 +1100
# 
#     powerpc/4xx: Fix build errors from mfdcr()
#     
#     lkp reported a build error in fsp2.o:
#     
#       CC      arch/powerpc/platforms/44x/fsp2.o
#       {standard input}:577: Error: unsupported relocation against base
#     
#     Which comes from:
#     
#       pr_err("GESR0: 0x%08x\n", mfdcr(base + PLB4OPB_GESR0));
#     
#     Where our mfdcr() macro is stringifying "base + PLB4OPB_GESR0", and
#     passing that to the assembler, which obviously doesn't work.
#     
#     The mfdcr() macro already checks that the argument is constant using
#     __builtin_constant_p(), and if not calls the out-of-line version of
#     mfdcr(). But in this case GCC is smart enough to notice that "base +
#     PLB4OPB_GESR0" will be constant, even though it's not something we can
#     immediately stringify into a register number.
#     
#     Segher pointed out that passing the register number to the inline asm
#     as a constant would be better, and in fact it fixes the build error,
#     presumably because it gives GCC a chance to resolve the value.
#     
#     While we're at it, change mtdcr() similarly.
#     
#     Reported-by: kernel test robot <lkp@intel.com>
#     Suggested-by: Segher Boessenkool <segher@kernel.crashing.org>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Acked-by: Feng Tang <feng.tang@intel.com>
#     Link: https://lore.kernel.org/r/20210218123058.748882-1-mpe@ellerman.id.au
# < /opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-gcc --version
# < /opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-ld --version
# < git log --format=%s --max-count=1 6a86fe746e2f69e49328b9ad8ad0f840c467ee59
# < make -s -j 10 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-  mmu_defconfig
# < make -s -j 10 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-  help
# make -s -j 10 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-  olddefconfig
# make -s -j 10 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-  
Kernel: arch/microblaze/boot/linux.bin is ready  (#1)
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_mmu_defconfig_microblaze
# Build took: 0:01:10.902944